In an Organic Light-Emitting Diode (OLED), the hole mobility of the hole transport material is much larger than the electron mobility of the electron transport material, and this causes an imbalance between the numbers of electrons and holes in the composite region and lowers the composite probability of excitons, thus the current efficiency and power efficiency of the OLED will be low.
In the prior art, in order to improve the electron injection and transportation capacity in an OLED, the following two methods are usually employed:
A method of employing N-type doping in the electron transport layer: as shown in FIG. 1, an N-type dopant 11 is doped in an electron transport material 12 according to a certain ratio. This is realized via coevaporation, but an accurate doping ratio of the N-type dopant to the electron transport material is required. This is difficult to be controlled during practical operation, and the repeatability of the experiment is poor.
A method of employing double electron injection layers: although the injection potential barrier of electrons may be lowered by this method, which is favorable for direct injection of electrons, the mobility of electrons in the transport layer cannot be improved.